What to Know About Mucolytics

Mucolytics are a class of drugs used to help break up and thin mucus, making it easier to clear from the airways. They are used to treat respiratory conditions such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, and other conditions including common colds marked by excess mucus and a productive cough. Types of mucoactive agents include expectorants, mucolytics, mucoregulators, and mucokinetics, and they are often taken orally or breathed in via a nebulizer. Mucolytics work best if taken consistently.

Overproduction of mucus in the lungs—usually seen with COPD or sometimes with a lower respiratory infection—is caused by inflammation that results in an increase in both the number and size of so-called goblet cells that line the air passages. While goblet cells normally secrete mucus as a form of protection, with COPD, for example, the excessive production can clog the passages, making it harder to breathe.

One way of clearing this buildup is with an oral or nebulized drug called a mucolytic. Mucolytics work by dissolving the chemical bonds within the secretions, breaking them so they can be more readily coughed up.

While mucolytics are not considered part of the current standard of care for COPD treatment, the 2017 guidelines issued by the Global Initiative for Obstructive Lung Disease (GOLD) suggest that the drugs may be useful in people who can't take inhaled corticosteroids. They may also be helpful for those who have difficulty with handheld inhalers.

Given the concerns about the safety of long-term corticosteroid use, there have been suggestions that mucolytics may be appropriate in advanced COPD, wherein the risk of exacerbation is high irrespective of steroid use. Mucolytics may, in these cases, help reduce the number of exacerbations and offer some improvement in the quality of life.

One substudy associated with the Bronchitis Randomized on NAC Cost-Utility Study (BRONCUS) further concluded that, when used with an inhaled corticosteroid, mucolytic drugs may reduce COPD exacerbations by as much as 21%. 

Mucolytics can be taken orally in a tablet or syrup formulation, or inhaled through a nebulizer. Some of the more common types of mucolytics include:

• Mucinex (guaifenesin)
• Carbocisteine
• Pulmozyme (dornase alfa)
• Erdosteine
• Mecysteine
• Bromhexine
• Hyperosmolar saline
• Mannitol powder

Carbocisteine, for example, is a mucolytic that acts on the metabolism of the goblet cells and also offers antioxidant and anti-inflammatory benefits. Guaifenesin, by contrast, increases the water content of the mucus, thinning it out so that it can be coughed up.

Most mucolytics are very safe, but should not be used in children under 6. Do not take mucolytics if you have a stomach ulcer.

Consult your doctor or pharmacist before taking mucolytics if you are pregnant or breastfeeding.

Dosage of mucolytics depends on the type of drug you're taking and the condition you're taking it for, in addition to whether you're taking a pill, liquid, or using a nebulizer. As some mucolytics don't stay in the system very long, you may need to take them consistently for a period of time.

Talk to your doctor about the proper dosage, delivery method, and duration for your condition.

The side effects can also vary both by drug type and formulation. Broadly speaking, nausea and diarrhea are the most common side effects associated with tablets, while liquids may also cause bronchial spasms and rashes. Nebulized formulations can similarly cause a sore throat, runny nose, and the formation of white patches in the mouth or lips.

By and large, mucolytics are considered safe and associated with a low risk of adverse events. With that being said, it's always important to speak with your doctor about any side effects, interactions, or contraindications associated with a mucolytic product, whether prescribed or purchased over the counter.